Through a Phase I STTR grant, we developed a blood-based enzyme-linked immunosorbant assay (ELISA) to fulfill an important unmet need in public health efforts against occupational asthma. The ELISA quantitates antibodies that specifically recognize and bind to the self-protein, albumin, which has been modified by chemical reactivity with isocyanate, the most common chemical cause of occupational asthma. The innovative aspect of our ELISA is that it's based upon unique isocyanate-albumin conjugates, generated under exposure conditions designed to more faithfully replicate the in vivo microenvironment (eg, mixed vapor/liquid phase, low isocyanate dosage) than previously described methods. In Phase II studies, we will develop our isocyanate ELISA into a commercial kit, and a novel approach towards isocyanate asthma prevention, based on the following principals (1) Isocyanate chemicals are "man- made" and don't exist naturally, (2 )Humans don't normally make antibodies to isocyanate-modified albumin;they are triggered by exposure, (3 )Exposure is the best-recognized risk factor for the development of isocyanate asthma, and exposure reduction is the most effective and widely used prevention strategy, (4) Without ongoing exposure, specific antibodies are cleared from blood in a time-dependent manner. Isocyanate antibodies, thus provide information about the most important risk factor (exposure) for isocyanate asthma, and may form the basis of a novel approach to disease prevention. As an exposure biomarker, isocyanate antibodies reflect internal dosage, and may be more biologically relevant than contemporary exposure surveillance approaches based on (external) air sampling, which suffers inherent practical and technical limitations. Exposure bio-monitoring, based on specific antibodies, would help focus hygiene efforts in a cost-effective manner, identify exposure sources or routes (e.g. skin) missed by conventional air sampling, and provide a sensitive basis for evaluating exposure-intervention strategies. Applied together with conventional hygiene approaches, isocyanate ELISAs could be an important part of pro- active strategies, towards understanding / reducing workplace exposures and preventing isocyanate asthma. AIM 1. Define the analytical performance characteristics of the new HDI ELISA for measuring specific antibodies (IgG isotype) in human blood obtained by venipuncture. AIM 2. Determine the clinical performance characteristics of the new HDI-ELISA, in workers at risk from occupational exposure and different populations of control unexposed subjects. AIM 3. Establish the kinetics of HDI-albumin specific IgG appearance / disappearance from the peripheral blood, and the potential contribution of exposure via the skin. PUBLIC HEALTH RELEVANCE: This proposal "New Serodiagnostics for Isocyanate Exposure, a leading cause of occupational asthma" will develop a commercial ELISA, and a novel serology-based approach to chemical exposure surveillance. The test will be widely used in civilian (eg. auto, construction industries) and military (US Air Force, Navy) sectors to help prevent occupational asthma.